Analysis and Solutions for Apache Displaying PHP Code Instead of Executing It

Problem Phenomenon and Root Causes

When Apache server is improperly configured, accessing PHP files may result in direct display of source code instead of execution. This phenomenon typically indicates that Apache fails to correctly recognize and process PHP script files. From a technical perspective, this primarily stems from the PHP processing module not being properly loaded or configured in Apache.

Core Configuration Verification

First, it is essential to verify whether Apache has loaded the PHP module. The Apache configuration file must contain correct module loading directives. For PHP 5 environments, typical configuration should include:

LoadModule php5_module "C:/php/php5apache2_2.dll"
AddType application/x-httpd-php .php
PHPIniDir "C:/php"

The LoadModule directive is responsible for loading the PHP module, and the path must point to an actual existing module file. The AddType directive defines which file extensions Apache should recognize as PHP scripts.

Module Status Validation

In Unix/Linux systems, PHP module activation can be confirmed by checking the /etc/apache2/mods-enabled/ directory. This directory should contain symbolic links pointing to PHP modules. Absence of relevant files indicates that the module has not been activated.

Error Log Analysis

Apache error logs serve as crucial tools for problem diagnosis. Examining the /var/log/apache2/error.log file provides detailed error information. Common errors include module loading failures, path errors, or permission issues. Warnings and error messages in the logs offer critical clues for problem localization.

Multi-Processing Module Configuration

In certain Apache configurations, particularly when using the mpm_event module, switching to the mpm_prefork module may be necessary to ensure proper PHP operation. Module switching can be achieved through the following command:

sudo a2dismod mpm_event && sudo a2enmod mpm_prefork && sudo a2enmod php7.0

Configuration Validation Methods

Creating test files containing the phpinfo() function is an effective method to verify PHP normal operation:

<?php
phpinfo();
?>

Save this file as info.php in the web root directory and access it through a browser. If the PHP configuration information page is displayed, it indicates that the PHP module has been correctly loaded and is running.

System Restart and Configuration Application

After modifying Apache configuration, the Apache service must be restarted to apply changes. Restart commands may vary across different systems:

sudo service apache2 restart  # Ubuntu/Debian
sudo systemctl restart apache2  # Systemd systems
httpd -k restart  # Windows systems

Compatibility Considerations

Ensuring PHP version compatibility with Apache version is crucial. Different Apache versions may require specific PHP module versions. For example, Apache 2.2 typically requires php5apache2_2.dll, while Apache 2.4 may need php5apache2_4.dll.

File Permission Verification

In Unix/Linux systems, ensure PHP files have appropriate read permissions. The Apache process user (typically www-data) must be able to read PHP file contents. Additionally, directories containing PHP files should have proper execute permissions.

MIME Type Configuration

Beyond basic AddType directives, more granular configuration can be achieved using the FilesMatch directive:

<FilesMatch \.php$>
SetHandler application/x-httpd-php
</FilesMatch>

This approach provides more flexible file matching mechanisms, capable of handling more complex file extension requirements.